Favorite: Definitely Shekka. Starting with the less sexually explicit stuff, her noble goal and good-natured heart made me fall in love with her almost immediately (go ahead, laugh; I'm a softie and a sucker for "Team Good Guys") and her sassy personality . The fear and concern that she expresses regarding her species' limited reproductive future goes a long way towards endearing her to the player (reader?... maybe both apply in this context), or at least that was the case for me. Then there's the fact that she's an engineer/mechanic, one of my absolute favorite character archetypes when it comes to an elaborated science-fiction setting. Suffice it to say, if she threw on a pair of glasses I'd probably drop whatever I was doing and marry her in a microsecond xD . Additionally, once you've successfully funded her project and recruited her, Shekka receives several bonus scenes involving her thoughts and feelings in regards to the experiences she's had on the various different planets you've taken her to (not to mention some of the interesting people you've introduced her to amongst your crew), which I felt was a really nice touch and helped to further flesh out an already well-defined character. Lastly, she's quite valuable as a crew member, being both a merchant and capable of small ship repairs over time; icing on the cake, if you'd like.
All in all, she's just a very pleasant and uplifting part of the overall TiTS experience; an adorable little spacebunny with a heart of gold.
Now onto the naughty stuff x3 .
While lagomorphs aren't at the tip-top of my favorites list when it comes to the whole "Anthro Spectrum", they're pretty high up there due to cuteness alone. Add in the fact that she also checks off more than a few of the Scalie boxes (that big, thick tail is especially nice <3) and you've got a great spacebabe on your hands... paws... claws... talons... whichever you prefer, dammit. Her sex scenes tend to lean on her cuteness quite heavily, which definitely works in her favor (and for me! xD). Then there's all the scenes wherein she acquires a massive horsedong, which are simultaneously hilarious and hot; another point scored for her when it comes to my tastes. To give you an example, my very first character ended up being a 7-foot-6 cow-taur, which itty-bitty Shekka then proceeded to fuck into the floor with the help of a step-stool. It was, in briefer terms, a very funny fap.
Stop it, quit looking at me like that.
Second Favorite: Reaha, probably. I liked the Cure Addiction path in her quest and it left me feeling really nice; I'm glad that I was able to do something good for her, especially after the hard life that the poor cow's lived. I was also pleasantly surprised to see that she was a soldier at one point in her past, an interesting little tidbit of backstory. The degree to which her former role as a sex slave has eroded her self-confidence was, in short, heartbreaking, so I was quite invested in her quest once it became clear to me that I could help her rise above her painful past. The genuine compassion and trust that she displays towards the player character only help to cement how kind and sensitive a soul she really is.
And no, I haven't experimented with turning her back into a sex slave. Not yet. I need a few drinks in me before I let the monster take control of the keyboard xD .
Sex-wise, she's a cow, so I was onboard with that shit immediately. Big, milky tits and cute-as-a-button sex? Yes, please.
Third Favorite: Gonna be brief here. Bess. Just imagine Data from Star Trek: The Next Generation, his desire to learn and become more human than his initial programming would allow, then toss in a metric shitload of sex. Very entertaining and very endearing.
Least Favorite?: I've seen a lot of comments in this thread picking Dr. Badger for this dubious honor, which I can understand but do not personally agree with. The negative aspects of her character strike me as too hilarious, so it's difficult for me to outright vilify her. The whole "Hey, kid, wanna be a hero?" schtick caught me off-guard the first time it happened and, sure, I reloaded my save file, but I still grinned in the end. I also thought it was funny that, once I did make a bimbo character on my own, my character was too bubble-brained to remember what the fuck Dr. Badger was even talking about.
So, if I were to pick a character or characters that I actively dislike, I'd probably pick the respective leaders of the Red and Gold Myr civilizations. Given the circumstances of their ongoing war, I found it sensible that the writers chose to have these leaders spout racist propaganda about each other in an attempt to better sway galactic travelers and representatives over to their own side of the conflict, but that doesn't mean I had to... you know... like it. However, I also felt like the entire point was to show that both governments were guilty of hypocrisy, so I can't very well blame my negative views regarding them on poor writing.
Thank you for reading my giant, stupid brick of text xD . If you'd like, you may use it to build a house.